The earth It is the third planet from the Sun, the fifth in the Solar System in terms of size and the one with the highest density.
Earth is the largest of the four rocky or terrestrial planets and the only known one that has life, although some of the other planets and satellites have atmospheres, they contain water and could harbor living beings
It rotates describing an elliptical orbit around its star, our Sun, about 150 million kilometers, in about a year. At the same time, it spins on its own axis every day.
The Earth is not a perfect sphere, since in the equator it thickens about 21 kilometers, the north pole is dilated 10 meters and the south pole is sunk about 31 meters. Its shape is called geoid.
The Earth has an atmosphere rich in oxygen, moderate temperatures, abundant water and a varied chemical composition. The planet is made up of rocks and metals, solid on the outside, but molten inside.
It also has a magnetic field, an ozone layer and an ionosphere that protect the earth's surface from harmful solar radiation and the impact of many meteorites.
Our planet formed about 4.550 million years ago and life emerged a billion years later. Here millions of species of living beings now live, including us humans.
According to current studies, it is believed that the Earth will be able to house life for some 500 million years. From then on, the radiation coming from the Sun will be too high to maintain life in the biosphere of our planet. There have already been several mass extinctions in the past; If life lasts until then, the extinction will be definitive.
Humans are visual beings and we have invented drawing. Since ancient times maps have been drawn up to represent the Earth. With the advent of photography, computers and astronautics, the earth's surface has been studied in detail, although much remains to be discovered.
The following pages explain the main features of the Earth.
In this chapter:Earth Movements: Translation and rotation are the two movements of the Earth that determine the duration of days and years ... Read pagePrecession and nutation: The previous page deals with the two most evident movements of the Earth, translation and rotation ... Read pageThe Earth: hydrosphere and atmosphere: Astronauts always speak of the Earth as "The Blue Planet", because of its color ... Read pageThe Earth's crust: The Earth is one of the solid planets or, at least, solid crust, already that not all layers are ... Read pageThe Earth's mantle and core: The Earth's crust is a very thin layer if we compare it with the planet's mantle and core ... Read pageMagnetism and electricity on Earth: The Earth behaves Like a huge magnet The English natural physicist and philosopher William… Read page Earth maps: The human being has always had the need to move from one place to another. Sometimes, looking for ... Read Page